1. Field of the Invention
The present invention relates generally to the field of single-supply integrated chips, and more particularly to a voltage clamping device within a single voltage-supply system to protect against over-voltage scenarios.
2. Background of the Invention
Numerous electrical devices, circuits, components and systems are designed to operate at or below a certain maximum voltage or current threshold. If the voltage or current should exceed this threshold, the device may be damaged or otherwise function improperly. A typical cause of an over-voltage or over-current scenario is a supply voltage or reference voltage malfunctioning and providing a voltage that is too high. Typically, an electrical device, such as an electrical circuit, has a voltage rating that refers to this maximum voltage or current threshold and provides information on the circuit's voltage sensitivity.
Over-voltage protection is oftentimes employed within a circuit to prevent voltage or current being supplied that exceeds this maximum supply voltage threshold. Over-voltage protection is usually triggered when a voltage or current, above a safe threshold level, is supplied to a circuit. Effectively, the over-voltage protection either reduces the amount of voltage or current being delivered to the circuit or completely isolates the circuit from the voltage or current supply. This over-voltage protection also allows a circuit to operate in a desired voltage range while protecting the circuit from large voltage or current swings on a supply that would otherwise damage the circuit.
Currently, over-voltage protection circuits use external supply voltages as a reference and the inclusion of these supplies into a system and on an integrated circuit may be both expensive and complicated.
Several techniques are currently being employed to protect integrated chips from over-voltages by external sources. These techniques include current or voltage attenuation. For example, input attenuation resistors may be implemented within a voltage or current source path to protect circuits from over-voltage or over-current conditions. However, these attenuation resistors draw static current from the input source resulting in both inefficiencies within the circuit as well as introducing unwanted design parameters such as noise, linearity, gain and offset error.
Therefore, what is needed is a device and method that allows a reduction in the number of independent voltage or current sources for a circuit and that provides over-voltage protection therein.